Free-to-play fighter Killer Instinct has for the first time switched the character available to everyone for free, rotating out Jago for lycanthrope Sabrewulf. You can still buy the fighting monk, of course. The change came with a new patch last week, which also brought tweaks and fixes and whatnot.
Microsoft has planned to rotate the free character regularly, letting people try more--and enticing them to buy them once they rotate out.
The patch notes (via Shoryuken) detail changes including fixing some moves which weren't supposed to be unbreakable, updating how many ranking points players win or lose in matches, and tweaking the balance a little.